The present invention relates to a device for locating position markers, and more particularly to a GPS device having an interface for communication with a position marker locator to associate GPS position data with the marker.
Position marking products are commonly used to mark the location of field features such as underground utility cables. These markers have traditionally been implemented as passive antennas that are locatable by transmitting an RF signal from a locator that is reflected by the marker back to the locator. The user of the locator is then able to document the position of the marker by employing cartographic or surveying equipment to determine the GPS coordinates of the locator and marker, and transcribing or electronically logging the coordinates that are determined. This equipment may be professional use equipment utilizing differential GPS technology, or may be a retail GPS receiver, depending on the accuracy required. After a number of markers have been located and their GPS coordinates have been determined, the list of coordinates can be manually uploaded into a mapping application, typically implemented as a software program on a personal computer (PC).
More advanced position markers have been recently introduced that have the ability to store data associated with the marker, so that data can be written to the marker and retrieved from the marker by a locator device. The data that is written and retrieved can also be stored in the memory of the locator device, for later uploading to a PC. While these markers have added utility to the locating process, the process required to determine GPS coordinates of the markers has remained substantially the same.
An exemplary existing locating system includes Dynatel™ locating devices manufactured by 3M Company of St. Paul, Minn. under the 2200M Series product name (for products capable of locating position markers and cables) or under the 1400 Series product name (for a product capable of locating position markers), and includes EMS position markers manufactured by 3M Company of St. Paul, Minn. under various product names. As mentioned above, GPS coordinates may be determined for the located markers by a separate, stand-alone GPS system, many of which are commercially available from various manufacturers, and the determined GPS coordinates are transcribed or electronically logged in a process separate from the location process. U.S. Pat. No. 5,576,973 to Haddy describes a system in which GPS coordinate data that is determined for a located marker is recorded in the marker.
It would be useful to provide position marker locating capability that is more efficiently able to determine the GPS coordinates of the markers.